Abstract/Summary

Despite the loss of CryoSat, ESA’s first Earth
opportunity mission, during its launch sequence in Oct
2005 ESA have been fortunate enough to have acquired,
processed to Level 1b and analysed a significant amount
of campaign data from ESA’s demonstration Airborne
SAR/Interferometric Radar Altimeter System (ASIRAS)
designed to have similar functionality to CryoSat’s
Synthetic Interferometric Radar Altimeter (SIRAL).
This data acquisition took place for the original purpose
of validating CryoSat retrievals.
Our initial analyses of the level 1b data have revealed
some very interesting results both over land and sea ice
test sites from respective campaigns conducted in the
Arctic during the land-ice spring/autumn campaigns of
2004 and for sea-ice in the Bay of Bothnia during
March 2005. Since a further ASIRAS campaign in the
Arctic is guaranteed for April/May 2006 we look at how
this data can be exploited in view of future ESA Earth
observation radar altimeter missions. Verification of the
ASIRAS data with coincident laser altimeter and in-situ
data collected at test sites is also presented.
The paper also provides a review of key space and air
borne radar altimeters dating from 1957 including those
using the synthetic aperture radar (SAR) technique as
applied to radar altimeters leading to the development of
CryoSat.